Recently I was diagnosed with an imbalance between my upper traps and my lower rhomboids (or whichever the lower muscles that retract the scapulae). Therapist recommends I strengthen those lower muscles and keep the upper traps as inactive as possible.
It THEN occurred to me...how about pre-exhausting them before every upper body workout? So, precede EVERY workout with an upper-trap holocaust, every set ending in failure, leaving them too tired to be recruited when I start the upper body work?
I'll look into what 'Facepulls' are, but DEFINITELY not Upright Rows...that's what got my Supra impinged in the first place. Granted I was keeping my elbows higher than my wrists, thus putting the shoulder joint in a suicidal angle, but I doubt it's wise to return to the scene of the crime.
If you want to correct the issue ASAP, it's probably a good idea to make it your number one short-term training priority rather than trying to squeeze the corrective work into whatever program you're currently doing.
Is it possible that your upper traps are overactive to reduce impingement on your supraspinatus? You may need to balance out your rotators and scapular depressors to hopefully create more space for the supraspinatus. Id probably drop (or at least limit) any overhead pulls (pullups/pulldowns) and work more on horizontal rowing/pulls. I have had this kind of problem before and pullups killed my shoulders more than bench press.
There are plenty of good suggestions here. Definitely DO NOT pre-fatigue traps, since pre-fatiguing will improve recruitment of those muscles in any of the exercises that follow.
If you try face pulls, make sure you pull to your mouth/chin area if you want to hit rhomboids. Pulling to the eyes will target rear delts. Going even higher will hit traps, which is absolutely not what you want to do if you are looking to avoid trap recruitment.
Im not a therapist of any kind so take my advice with a grain of salt and continue to look for further ideas and options. But these cant hurt (:
IMO its a matter of getting all the muscles to work optimally. Your Supraspinatus may be overactive as well, and taking on too much workload because the muscles around it are injured/balled up with trigger points or weak. Id make sure tissue quality around the shoulder is improved via foam rolling/trigger point work/massage/art etc and then strengthening all muscles that act on the scapular and depress the humerus.
In exercise terms this is what has helped me. Rows. Face pulls. Band pullaparts. Rows. Isometric holds at peak contraction with rowing movements (sub max weights) Strict Cable External Rotations. Limiting/avoiding overhead pulls. Rows. Shoulder dislocates. Rear delt flyes. Lateral Raises while trying NOT to hold shoulders down and allowing upper traps to work naturally as part of the movement. And last but not least... Rows. I definately think favouring rowing movements for back work over vertical overhead pulling is what helped me the most though. In your case youll probably need to lower the weight until you can pull equally with all the mid back muscles and not just traps. Use straps as well so you dont end up pulling with arms as much. I like to get bands and do some Rows with them to get my mind muscle connection with the mid back. Pause and hold at top of movement and really try to feel the mid back working. Ill sometimes do a set of these followed by a set of normal rows and trade back and forth. Also I think DB rows work better for me for mid back compared to BB.